Hi Ahmed

Welcome to the Forums.

A thread read over 100 times without reply which possibly indicates that readers are unsure about what you want to get across to your audience.

You could be concerned about the direct risks from welding (whatever method being used - and the method will result in some differences in the risks to the welders and those around them). 

However, you specifically mention tack welding rather than welding in general which might mean that the tack welding is being done to offer temporary security pending other operations to permanently secure components together - so part of a so called "Temporary Works" design.

If you are more concerned about the latter, then it is about what actions are needed to stop a parting of the components which in some circumstances could result in a catastrophic structural collapse.

If you aer looking for constructive help with your question, I suggest you clarify your objectives in putting together and delivering this training.

Might also be that somebody has asked you to develop these slides as a test of your own capabalities and if you find some generic slides from a reader on these Forums, that you are simply using somebody else's work might be obvious to whoever has asked you to do this task.

Good luck, Peter